1. Field of the Invention
The present invention relates to a measuring apparatus for inspecting a fixing state of an object to a supporting member, and more particularly to an oscillation degree measuring apparatus for inspecting a fixing state of a small object, such as the root of a tooth.
2. Related Background Art
A dental implant (the root of a tooth) is given as an example of an object whose fixing state is required to be measured. The fixing state can be thought of as the degree of oscillation of an object to be measured. The degree of oscillation means the amount of oscillation of the object to be measured when a certain shock is given to the object.
In general, if a natural tooth is lost due to a cavity in the tooth or by an accident, since the root of the tooth for supporting the crown is also lost, a treatment using a bridge or the like is performed. However, the bridge causes an excessive burden on the natural supporting teeth on both sides of the bridge, and shortens the lives of such supporting teeth.
In order to solve the above problem, a treatment which buries and fixes an implant for supporting the crown of a tooth in a jaw bone and mounts an artificial crown thereon has been studied, and many implants are now in practical use. When a certain kind of implant is used, it is necessary to measure the fixing state of the implant in an operation. For example, in the case of an implant which is directly joined with a jaw bone, if the implant is insufficiently buried and fixed in the jaw bone, soft tissue intrudes between the implant and the jaw bone, and the implant cannot be directly joined with the jaw bone and cannot effectively function. Therefore, it is essential to confirm that the implant is sufficiently fixed when it is buried.
However, it is difficult to measure the fixing state of the implant in a conventional measurement method. In other words, except for the case in which soft tissue between the implant and the jaw bone develops extremely thick, it is difficult to diagnose an insufficient fixing by a general X ray, and an X-ray image gives only information as to the vicinity of an outline of the implant. On the other hand, a measurement method which applies a strong force to the implant is likely to break the fixing state which has been obtained.
The inventors of the present invention invented an apparatus for measuring slight oscillations of an implant by ultrasonic waves and diagnosing the fixing state of the implant, which has been already disclosed in Japanese Patent Application Laid-open No. 60-190941.
The disclosed apparatus transmits ultrasonic oscillations, which are generated from an ultrasonic oscillation source and include at least a predetermined resonant frequency element, to an implant buried in a jaw bone through an ultrasonic wave transmitting means, detects the oscillations excited by the implant by a detection means, converts a resonant phenomenon at the above predetermined resonant frequency into electrical signals and observes the electrical signals, and diagnoses the fixing state of the implant based on whether or not the resonant phenomenon is present.
However, in such a conventional apparatus which observes ultrasonic oscillations, since electrical signals representative of the oscillations of the implant are observed by an oscilloscope, the oscillation waveforms include much information while they include unnecessary information, and a processing method of received signals is not sufficiently established, it is difficult to objectively judge numerical values of the degree of oscillation representing the fixing state and to aptly evaluate the fixing state.